Iraqi forces began a key push in the campaign to take back the ISIS-held city of Fallujah, west of Baghdad, on Monday.

Uncredited / AP

The city has been under ISIS control for more than two years. The bid to take it back is being supported by paramilitary troops, and is receiving aerial assistance from the U.S.-led coalition. On Sunday, four airstrikes hit two ISIS tactical units near Fallujah, according to the coalition, destroying three vehicles and a tunnel entrance.

Fallujah is considered important to ISIS because it acts as a staging ground from where they plan and undertake attacks in Baghdad and Sadr City.

Earlier this month, Baghdad and Sadr City were hit by three bombs in the space of just a few hours, killing 80 people on the deadliest day the Iraqi capital had seen in a year.

If the recapturing of Fallujah is successful, ISIS will be pinned back towards the city of Mosul, which effectively acts as the capital of the territory the group has seized in Iraq. This would mean the Islamist group would have greater difficulty gaining more territory across the country.

It would also be a symbolic boost to the Iraqi government, as Fallujah was the first city to fall to ISIS.